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November 4, 2012, 11:40 am

Scott L

Question: 2000 Hyundai elantra fuel pump

My fuel pump doesn't seem to kick on. Car ran fine, stalled and won't start now. It does turn over but no start. Replaced relay and same problem. Took out pump and ran constant 12v to pump. It does work.

It sends out the RPM signal to the PCM. If it is bad, there is no RPM signal, and the PCM will not command the injectors to fire. Easiest way to see if it works is to hook up a scantool and crank the engine. Monitor the datastream for RPM. If you see RPM then the sensor is working, if it reads zero RPM, then there is a problem with the Crank Position Sensor circuit.

If you don't have a scantool, you could just replace it and see what happens. Most are under $30.

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November 9, 2012, 5:16 pm

Scott L

Ok i know how to check that with a multi meter. My fuel pump wrong come on with the key but will if i run a wire from the positive side of the battery too the fuel pump. I replaced the relay and there is no fuse or cut off switch for the fuel pump to my knowledge. Would the crank sensor cause that as well?

Will the car run with the fuel pump powered up directly? If it will, the crank position sensor is probably OK. It kills the injectors on most vehicles. I wold see if there is power getting to the rely with the car cranking. If not, you have an ignition feed issue. If i does, then it probably is a wiring issue between the relay and the pump.

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November 9, 2012, 6:00 pm

Scott L

No it won't start with the pump going. I get what your saying and I'll check the crank sensor tomorrow. But for the fuel pump, is there an easy way to find out if the problem is in the ignition or the wiring between the relay and pump?

Testing at the relay is the first step. Make sure there is battery voltage at one terminal and an ignition feed when cranking, That breaks the circuit in two.

If it's good, check power at the pump. If there isn't power start tracing back.

If the ignition feed is bad, check the output voltage at the ignition switch. and work toward the relay from there.

If the battery feed is bad, check the fuse that feeds the circuit and work from there.

One other quick thing you can do is put a fused jumper across the fuel pump Bat feed circuit to the wire that goes to the pump. If the pump runs, then the wiring to the pump (and the pump) are most likely OK.

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